Mcreator just not making plugins!

Hi I'm using Mcreator 2021.3 and a new and fresh version of java 8 (I have tried other java versions), I also have the newest Spigot api for making plugins.
Still, somehow, EVERY TIME I so much as TRY to make a plugin, this happens:

*What went wrong:
Could not initialize class.org.codehaus.groovy.reflection.ReflectionCache

I have tried:

Loads of Java versions.
Uninstalling and reinstalling.
Restarting computer.
Using older versions of Mcreator.
Dancing.

(None worked)

Please help me...